When a small group of runners gathered on a cold autumn morning in London 20 years ago, little did they know they were taking part in an event that would become an international hit.
Green Day’s album American Idiot has just hit number one, Ben Stiller’s Dodgeball is showing in cinemas and the first series of Strictly Come Dancing has finished.
Organizer Paul Sinton-Hewitt persuaded 13 pioneering runners to come to what became known as the Bushy Park Time Trial on 2 October 2004 after injuries prevented them from taking part.
“It really affects people’s lives so that the good that happens in the park on Saturday morning extends to the whole week,” he said of the event with millions of participants and volunteers each week.
For the uninitiated, Parkrun sees people of all ages and abilities gather outdoors at 9am on a Saturday and run 5km – or just over three miles.
A shorter 2km run for four to 14-year-olds and their families takes place on Sunday mornings.
By Christmas 2004, the figure was doubled and by the time of the 2012 Olympics the event had been extended to every borough of London.
Last month, Lithuania became the latest country to host Parkrun, bringing the total number of countries to 23.
Ireland is the most popular place for Parkrun in the world – with between 8-9% of the population registered.
In London, where it all started, there are now almost 750,000 registered parkrunners (including Greater London) and about 100 events every weekend.
Born in Zimbabwe but raised in South Africa, Mr Sinton-Hewitt awarded a CBE for services to grassroots sports participation in 2014.
Now enjoying living in the Sussex countryside, he says “you get absorbed by the community, it makes you feel special”.
She said: “Almost everyone I know has found that they really like it.
“It’s not competitive. You can run as hard as you want. You can be as competitive as you want but you’re not competing with anybody.
“You’re competing with yourself, and as a result, there’s this pressure taken and it’s just fun, right?”
Parkrun: In numbers
10,000,000: Registered Parkrunners
900,000: Volunteers
2,500: Parkrun locations
2,000: Operation GP is linked to Parkrun
25: Parkruns in prisons and young offender institutions
23: Country where Parkrun takes place
Source: Parkrun
Six years ago, Afe Komolafe was pre-diabetic and started doing Parkrun near her home in Hayes, west London.
The community engagement officer loves the weekly event and, after a brief break due to a knee injury, is now taking part in the first person and even traveling abroad with friends he made at the event to get his Parkrun fix.
He said: “Parkrun means a lot to me. It’s community, friendship, health, wellbeing, fitness.
“It’s just special. It’s run by volunteers: there’s no air or grace about it.
“I’ve made a lot of friends through Parkrun.”
Nigel Rata, who has a PhD in atmospheric chemistry, has clocked up more than 200 events and is trying to “get Parkrun wherever I am”.
The south Londoner describes it as “family”.
He said: “There’s no expectation of what you do when you get there. There’s no performance expectation…but the bottom line, there is for me.
“You’re going to feel good no matter what you’re feeling.
“Being with people who are outdoors and getting fresh air in a green space just works for me.”
For the man who started it all, arthritis in his left knee means he “can still walk, but mostly walking or I’m back volunteering”.
Mr. Sinton-Hewitt said: “It helps me see the joy in life and and sets my way out for the rest of the week, so it is a very important part of my life.”